410 research outputs found
High-power CW ultraviolet ion lasers
Over 1 watt of continuous ultraviolet output has been obtained from an argon ion laser in the 3500-3700Å range. This paper describes the discharge tube structure used and the operating characteristics of high-power ultraviolet laser transitions in argon and other noble gas ions. Operation at new wavelengths as well as CW operation of transitions previously observed only in pulsed operation are reported. Measurements of the dependence of spontaneous emission intensity from different ionization states on current and pressure are related to the excitation mechanisms for visible and uv ion lasers. The technique of population modulation by intracavity interruption has been used to study processes in the throat and uniform bore regions of ion laser discharges. The results of these studies are described. Problems encountered in the CW operation of ion laser discharge tubes at current densities above 1000Å/cm^2 are described
A microfluidics and agent-based modeling framework for investigating spatial organization in bacterial colonies: The case of Pseudomonas Aeruginosa amd H1-type VI secretion interactions
The factors leading to changes in the organization of microbial assemblages at fine spatial scales are not well characterized or understood. However, they are expected to guide the succession of community development and function toward specific outcomes that could impact human health and the environment. In this study, we put forward a combined experimental and agent-based modeling framework and use it to interpret unique spatial organization patterns of H1-Type VI secretion system (T6SS) mutants of P. aeruginosa under spatial confinement. We find that key parameters, such as T6SS-mediated cell contact and lysis, spatial localization, relative species abundance, cell density and local concentrations of growth substrates and metabolites are influenced by spatial confinement. The model, written in the accessible programming language NetLogo, can be adapted to a variety of biological systems of interest and used to simulate experiments across a broad parameter space. It was implemented and run in a high-throughput mode by deploying it across multiple CPUs, with each simulation representing an individual well within a high-throughput microwell array experimental platform. The microfluidics and agent-based modeling framework we present in this paper provides an effective means by which to connect experimental studies in microbiology to model development. The work demonstrates progress in coupling experimental results to simulation while also highlighting potential sources of discrepancies between real-world experiments and idealized models
Effects of vitamin E supplementation on renal non-enzymatic antioxidants in young rats submitted to exhaustive exercise stress
<p>Abstract</p> <p>Background</p> <p>Exercise stress was shown to increase oxidative stress in rats. It lacks reports of increased protection afforded by dietary antioxidant supplements against ROS production during exercise stress. We evaluated the effects of vitamin E supplementation on renal non-enzymatic antioxidants in young rats submitted to exhaustive exercise stress.</p> <p>Methods</p> <p>Wistar rats were divided into three groups: 1) control group; 2) exercise stress group and; 3) exercise stress + Vitamin E group. Rats from the group 3 were treated with gavage administration of 1 mL of Vitamin E (5 mg/kg) for seven consecutive days. Animals from groups 2 and 3 were submitted to a bout of swimming exhaustive exercise stress. Kidney samples were analyzed for Thiobarbituric Acid Reactive Substances to (TBARS) by malondialdehyde (MDA), reduced glutathione (GSH) and vitamin-E levels.</p> <p>Results</p> <p>The group treated with vitamin E and submitted to exercise stress presented the lowest levels of renal MDA (1: 0.16+0.02 mmmol/mgprot vs. 2: 0.34+0.07 mmmol/mgprot vs. 3: 0.1+0.01 mmmol/mgprot; p < 0.0001), the highest levels of renal GSH (1: 23+4 μmol/gprot vs. 2: 23+2 μmol/gprot vs. 3: 58+9 μmol/gprot; p < 0.0001) and the highest levels of renal vitamin E (1: 24+6 μM/gtissue vs. 2: 28+2 μM/gtissue vs. 3: 43+4 μM/gtissue; p < 0.001).</p> <p>Conclusion</p> <p>Vitamin E supplementation improved non-enzymatic antioxidant activity in young rats submitted to exhaustive exercise stress.</p
Monilochaetes and allied genera of the Glomerellales, and a reconsideration of families in the Microascales
We examined the phylogenetic relationships of two species that mimic
Chaetosphaeria in teleomorph and anamorph morphologies,
Chaetosphaeria tulasneorum with a Cylindrotrichum
anamorph and Australiasca queenslandica with a Dischloridium
anamorph. Four data sets were analysed: a) the internal transcribed spacer
region including ITS1, 5.8S rDNA and ITS2 (ITS), b) nc28S (ncLSU) rDNA, c)
nc18S (ncSSU) rDNA, and d) a combined data set of ncLSU-ncSSU-RPB2 (ribosomal
polymerase B2). The traditional placement of Ch. tulasneorum in the
Microascales based on ncLSU sequences is unsupported and
Australiasca does not belong to the Chaetosphaeriaceae. Both
holomorph species are nested within the Glomerellales. A new genus,
Reticulascus, is introduced for Ch. tulasneorum with
associated Cylindrotrichum anamorph; another species of
Reticulascus and its anamorph in Cylindrotrichum are
described as new. The taxonomic structure of the Glomerellales is
clarified and the name is validly published. As delimited here, it includes
three families, the Glomerellaceae and the newly described
Australiascaceae and Reticulascaceae. Based on ITS and ncLSU
rDNA sequence analyses, we confirm the synonymy of the anamorph genera
Dischloridium with Monilochaetes. Consequently
Dischloridium laeënse, type species of the genus, and three
related species are transferred to the older genus Monilochaetes. The
teleomorph of D. laeënse is described in Australiasca
as a new species. The Plectosphaerellaceae, to which the anamorph
genus Stachylidium is added, is basal to the Glomerellales
in the three-gene phylogeny. Stilbella annulata also belongs to this
family and is newly combined in Acrostalagmus. Phylogenetic analyses
based on ncLSU, ncSSU, and combined ncLSU-ncSSU-RPB2 sequences clarify family
relationships within the Microascales. The family
Ceratocystidaceae is validated as a strongly supported monophyletic
group consisting of Ceratocystis, Cornuvesica,
Thielaviopsis, and the type species of Ambrosiella. The new
family Gondwanamycetaceae, a strongly supported sister clade to the
Ceratocystidaceae, is introduced for the teleomorph genus
Gondwanamyces and its Custingophora anamorphs. Four families
are accepted in the Microascales, namely the
Ceratocystidaceae, Gondwanamycetaceae,
Halosphaeriaceae, and Microascaceae. Because of a suggested
affinity of a Faurelina indica isolate to the Microascales,
the phylogenetic position of the Chadefaudiellaceae is reevaluated.
Based on the results from a separate ncLSU analysis of the
Dothideomycetes, Faurelina is excluded from the
Microascales and placed in the Pleosporales
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